Process and apparatus for reordering expanded tobacco

ABSTRACT

A process reorders tobacco that has been expanded by impregnating the tobacco under pressure with liquid carbon dioxide, forming a frozen mass of the tobacco and carbon dioxide, and heating the frozen mass in an expansion zone to sublimate the carbon dioxide and thereby expand the tobacco. The expanded tobacco is discharged from the expansion zone and before the temperature of the expanded tobacco is below about 80° F. and preferably when the expanded tobacco is at an elevated temperature of between about 180° F. and about 212° F., the tobacco is contacted with humidifying air having a temperature of about 80° F. to about 91° F. and a relative humidity of about 58% to about 88%.

RELATED APPLICATION

[0001] This application is a continuation-in-part of application Ser. No. 10/161,793 filed Jun. 4, 2002, the disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a process for reordering tobacco, and in particular to a process for reordering cut tobacco filler after carbon dioxide expansion.

[0003] The filling power of cut tobacco filler is frequently increased prior to incorporation into cigarettes. Often, this increase in filling power is achieved by impregnating the filler with an impregnant followed by subjecting the filler to conditions under which the impregnant is rapidly transformed into a gaseous state, thereby expanding or “puffing” the cellular structure of the filler.

[0004] In one of these processes, known as the dry ice expanded tobacco process, or DIET process, tobacco cut filler is sealed in a pressure vessel, which is pressurized to from about 300 to about 500 psi. Liquid carbon dioxide is introduced into the vessel to impregnate the cut filler then drained under pressure. The vessel is then depressurized to convert the liquid CO₂ to solid CO₂ resulting in a frozen mass of tobacco cut filler and solid CO₂, or dry ice. This mass, which may be first subdivided into pieces, is introduced into a sublimator or expansion zone in which the mass is subjected to a high temperature of about 400° F. to about 700° F., resulting in rapid conversion of the solid CO₂ to gaseous CO₂ and the expansion of the tobacco filler.

[0005] Tobacco discharged from the sublimator normally has a temperature of from about 180° F. to 250° F. and typically about 200° F. The moisture content of the expanded filler is about 2-6% wt., or less, making the tobacco filler very fragile and susceptible to shattering.

[0006] In order to render the filler suitable for subsequent processing into cigarettes, the moisture content of the filler is increased, normally to about 12-14% wt. In this process, known as “reordering” in the industry, the dry filler is cooled to ambient temperature, typically about 80° F., before being subjected to a high moisture content environment. For example, the tobacco can be tumbled in a rotating cylinder while being treated with steam or a fine spray of water.

[0007] Conventional expanded tobacco reordering processes have had two major disadvantages. First, in some processes, considerable time is required to increase the moisture content from the 2% or so level to the desired 12-14% level. In addition, reordering causes some collapse of the cellular structure of the expanded tobacco, resulting in a significant loss in the filling power that was initially achieved during the expansion stage. Conventionally reordered expanded tobacco typically has a filling value of from about 630 to about 680 cc/100 gm.

[0008] Various alternative processes have been proposed to address one or both of these deficiencies. For example, U.S. Pat. No. 5,383,479 to Winterson et al. describes a process for reordering dry ice expanded tobacco in which the expanded tobacco, after first being cooled to ambient temperature of about 80° F., is carried on a belt dryer through zones of increasing humidity ranging from an initial humidity of about 30% RH, increasing to about 60% RH. During reordering, the tobacco is conveyed along the belt dryer through the different humidity zones in which humidified air at a temperature of 75° F. to 95° F. is blown downwardly onto, or upwardly through, the tobacco. The moisture content of the expanded tobacco is gradually increased as the expanded tobacco equilibrates with the prevailing humidity of each humidity zone. The expanded tobacco is subjected to a series of increasing humidity zones until the moisture content of the expanded tobacco is gradually ramped up to the desired moisture content level. Total time required to ramp the moisture content of the expanded tobacco to the desired 12-14% level is from 30 to 90 minutes. Tobacco reordered in this manner is said to have no statistically significant loss of filling power as determined by standard analysis of variance procedure.

[0009] Even if the process described in the preceding patent is effective in reordering tobacco filler without loss in filling power, there is still a need for a process in which reordering without significant filling power loss can be achieved in a significantly shorter time than the minimum 30 minutes required for the above process.

[0010] In addition, conventional expanded tobacco reordering processes such as the process disclosed in the Winterson et al. patent have demonstrated a high propensity for fire propagation in the tobacco bed after the tobacco is discharged from the sublimator. In these processes, tobacco having an elevated temperature of between about 180° F. and 250° F. and relatively low moisture content of between about 2-6% wt. is discharged from the sublimator onto a conveyer. Frequently, hot embers from the sublimator are intermixed with the expanded tobacco as it is discharged from the sublimator and transferred on the conveyor belt leading to the humidifying zone. Due to the relatively low moisture content and elevated temperature of the expanded tobocco, the hot embers have a tendency to ignite the tobacco. Furthermore, due to the compact nature of the tobacco bed on the conveyor belt any ignition of the tobacco propagates rather quickly throughout the tobacco bed. Therefore, a need exists for a reordering process that prevents the propagation of fires in the bed of expanded tobacco after it is discharged from the sublimator.

SUMMARY OF THE INVENTION

[0011] Using the present process, it is possible to reorder expanded tobacco to a moisture level of 12-14% in less than 20 minutes with reduced loss of filling power. This unexpected result is achieved by subjecting the expanded tobacco to defined humidity conditions after the expanded tobacco is removed from the sublimator and before the temperature of the expanded tobacco has cooled below about 80° F.

[0012] More specifically, a bed of cut tobacco filler that has been expanded by the dry ice expansion process, or DIET process, is initially humidified before significant cooling, i.e., when the expanded tobacco is between about 180° F. and about 212° F., by blowing air having a temperature of 80-91° F. and about 58 to about 88% RH through the tobacco bed. The humidified air is blown through the tobacco bed for about 6 up to about 20 minutes. Preferably, the tobacco bed has a thickness of from about 0.10 to about 20 inches.

[0013] For example, the hot, expanded tobacco filler may be discharged directly from the sublimator onto a moving belt conveyor, which may be air permeable, or onto a vibrating conveyor, to carry the filler through a humidity zone in which air is blown down onto, or up through, the tobacco on the conveyor. Upon being discharged from the sublimator, the expanded tobacco typically has an elevated temperature of between about 180° F. and about 250° F. According to a preferred embodiment of the present invention, the expanded tobacco on the conveyor has a temperature of at least 180° F., and preferably between about 180° F. and about 212° F., when first contacted with the humidified air. The operation of the conveyor is adjusted so that any given part of the tobacco remains within the humidity zone for about 6 to about 20 minutes. Preferably, the tobacco stays in the humidity zone for about 11 minutes. Typically, uniform humidity of the air is maintained across the zone. Air velocity is normally in the range of from about 10 CFM to about 120 CFM per sq. ft. of bed, and preferably in the range of from about 90 CFM to about 120 CFM per sq. ft. of bed. As the invention is practiced with different volumes of tobacco, specific air velocities within these ranges may be desirable. For example, with a tobacco bed having a thickness of about 9 inches, the air velocity is preferably about 110 CFM per sq. ft. of bed.

[0014] A preferred embodiment of the invention also provides an apparatus for expanding and reordering tobacco. A tobacco expander has an expansion zone to expose tobacco impregnated with an impregnant to heat to sublimate the impregnant from the tobacco to cause tobacco expansion, resulting in expanded tobacco having an elevated temperature of between about 180° F. and about 250° F. A reordering zone downstream of the expansion zone is close enough to the discharge outlet of the expansion zone so that the expanded, elevated temperature tobacco remains at an elevated temperature of between about 180° F. and about 212° F. when it reaches the reordering zone. The reordering zone includes a blower to blow humidified air through the expanded, elevated temperature tobacco in the reordering zone.

[0015] Alternatively, the expanded tobacco may be discharged from the sublimator and transported in an enclosed heated conveyor to a reordering zone. The enclosed conveyor is externally heated to maintain the elevated temperature of the tobacco between about 180° F. and about 212° F. until it is reaches the reordering zone. The conveyor may be belted or vibratory. The reordering zone includes a blower to blow humidified air through the expanded, elevated temperature tobacco.

[0016] A preferred embodiment of the invention provides reordered expanded tobacco with a filling value of about 750 cc/100 gm, a 10-19% improvement over conventional processes.

[0017] The present invention also provides a process and apparatus for preventing the propagation of fire in the expanded tobacco bed after it is discharged from the sublimator. Specifically, the bed of expanded tobacco and any hot embers discharged from the expansion chamber are fluidized by the high velocity humidified air stream blown through the conveyor carrying the tobacco bed. Since the expanded tobacco fibers and any hot embers from the expansion zone are rapidly mixed in the fluidized bed, fire propagation is eliminated because the hot embers have little if any contact with the tobacco fibers, and are quickly consumed by their own fire.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a schematic view of the apparatus used to practice the present process.

[0019]FIG. 2 is a graphical representation of corrected filling values obtained at various combinations of relative humidity and temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The present invention relates to a process and apparatus for reordering cut tobacco after it has been subjected to an expansion process to increase the filling power of the tobacco. A preferred embodiment of the present invention will be described with reference to the general schematic shown in FIG. 1. As an example, filler tobacco having a cut-width of 32 cuts per inch is impregnated with liquid CO₂ in a pressurized vessel 10. The CO₂ impregnated tobacco, containing approximately 23% moisture and 11% carbon dioxide, is heated in a sublimator 12 using air and steam heated to a temperature of 343° C. (640° F.) to convert the CO₂ from its solid state to a gaseous state, thereby expanding the tobacco. Although carbon dioxide is currently preferred by the tobacco industry as the change of state medium, other materials have been used and it is expected that the reordering process described herein is useful for them, as well.

[0021] The expanded tobacco, having a temperature upon exiting sublimator 12 of from about 180° F. to about 250° F., is then discharged through rotary lock 14 of sublimator 12 directly onto the entrance end 18 of a 1×12 foot vibratory conveyor 16. Other sizes of vibratory conveyors can be used. The expanded tobacco forms a tobacco bed on the vibratory conveyor 16 having a depth of between about 0.10 inch and about 20 inches, and preferably about 9 inches. In the preferred embodiment of the present invention, air having a relative humidity of about 78% and a temperature ranging from about 80° F. to about 91° F. is then blown upwardly through the screened bottom of vibratory conveyor 16 at a rate of between about 10 and 120 CFM per sq. ft. of bed, and preferably between about 90 and 120 CFM per sq. ft. of bed. Preferably, the tobacco bed is initially contacted by the humidified air stream when it is at an elevated temperature of from about 180° F. to about 212° F. The tobacco is levitated and reordered by the warm moist air, with the mechanical action of vibratory conveyor 16 carrying the tobacco from the entrance end 18 to the discharge end 20 of conveyor 16 over a period of from about 6 to about 20 minutes preferably about 11 minutes.

[0022] It will be understood that the temperature of the bed of expanded tobacco steadily decreases as it is being contacted with the humidified air. For example, the expanded tobacco will decrease from an elevated temperature of between about 180° F. and about 212° F. to an ambient temperature of about 90° F. after several minutes of continuous contact with air having a relative humidity of 78% and a temperature of about 90° F. The applicants have unexpectedly found that the expanded tobacco at elevated temperatures ranging from about 180° F. to about 212° F. will quickly gain moisture when contacted with humified air. For example, the moisture content of expanded tobacco at temperatures between about 180° F. to about 212° F. will increase by about 3% to 5% wt. almost immediately after being contacted with air having a relative humidity of 78% and a temperature of 90° F. The moisture content of the expanded tobacco will continue to increase as the tobacco is further contacted by the humidified air and the temperature of the expanded tobacco decreases to ambient temperature of about 90° F.

[0023] The tobacco is caused to move to the discharge end 20 of conveyor 16 due to the fluidization of the bed, coupled with vibration of conveyor 16. As the depth of tobacco builds at the entrance end 18, gravity evens out the bed depth by moving the tobacco towards the discharge end 20. This may be aided by sloping the conveyor 16 downwardly from entrance end 18 to discharge end 20. Retention time and bed depth can be varied and controlled using dams, weirs, and other devices on the bed surface.

[0024] Multiple samples collected from tests at various temperatures and relative humidities were measured for Corrected Fill Value (CFV) at different filling values at a 0.5 lb./minute flow rate. The results depicted in FIG. 2 were obtained. Three additional tests were conducted at 78% RH and a flow rate of 0.25 lb./min., with the following results: ° F. CFV 87 748.5 87 758.2 89 730.3

[0025] Filling Value and Moisture Measurement Procedures

[0026] Ten tobacco samples were collected for each Fluidized Bed test. One corrected filling value (CFV) measurement was performed on each of the tobacco samples collected. Two moisture analyses were performed on the tobacco used to conduct each CFV measurement. A Sartorius Basic balance was used to determine each moisture tin's tare weight. The moisture tin identifications and weights were recorded.

[0027] A Model 5000 Specific Volume Electronic Readout Unit was used for the filling value measurements. The procedure used was documented in SOP: QAS-MC-44 “Filling Value of Cut Tobacco-QA.” This machine requires 30-minutes to warm-up, and its accuracy is verified against a set of standards before each use. The expanded tobacco samples were mixed to achieve a homogeneous mixture. A Mettler P1200 balance was used to determine each sample's weight before its filling value was measured. The weight of each sample, and the filling value measurement were recorded. The tobacco used for each filling value measurement was placed into two moisture-tins, and the tins were weighed. The moisture-tin weights and tobacco identification were recorded.

[0028] The moisture tins were placed in a Lab-Line Ultra-Clean oven, Model #3499M-3 for drying. The oven temperature was set for 105° C., and the timer was set to maintain this temperature for eight hours (11:00 PM-7:00 AM). The moisture-tins were removed from the oven, the lids were replaced, and the tins were allowed to cool. The moistures and the corrected filling values were calculated for each tobacco sample. The Specific Volume Readout Unit used for this analysis was designed to measure the corrected filling value of tobacco when used in conjunction with the following Corrected Filling Value Formula:

[0029] Corrected Filling Value Formula:

((TTW/ATW)*UFV)*E ^(((s)*((TM−AM))=) CFV

[0030] Abbreviation Key:

[0031] TTW=Theoretical Tobacco Weight

[0032] ATW=Actual Tobacco Weight

[0033] UFV=Uncorrected Filling Value

[0034] CFV=Corrected Filling Value

[0035] S=Slope of Moisture Correcting Curve

[0036] AM=Actual Moisture

[0037] TM=13.5%=Theoretical Moisture

[0038] The theoretical tobacco weight (75 g) is divided by the actual tobacco weight (70.6 g), resulting in the ratio of theoretical to actual weight.

[0039] The ratio of Theoretical Tobacco Weight: 75/70.6=1.0623229

[0040] The 70.6 g tobacco sample had an actual filling value of 653.646 cc. The Specific Volume Electronic Readout Unit divides (via instrument calibration) this sample (volume and weight) by a factor of 0.75 changing the volume to 820.40 cc (Uncorrected Filling Value). The result of multiplying the ratio of theoretical tobacco weight (1.0623229) by the uncorrected filling value is the filling value corrected to 100-grams (Weight Corrected Filling Value).

[0041] Weight Corrected Filling Value: ((1.0623229)*820.40)=871.529 cc/100 g

[0042] The weight corrected filling value was further adjusted based on the tobacco's moisture content. A Moisture Correction Curve was generated from filling value analyses of the same tobaccos having various moisture contents. For example, filling value analyses of six to eight tobacco samples distributed across a moisture range of 10 to 16% would be sufficient to generate a Moisture Correction Curve. The two axes of this curve would consist of Moisture (%) plotted against the Corrected Filling Value (cc/100 g). The slope of the Moisture Correction Curve would then be used in conjunction with the actual moisture content to calculate the Corrected Filling Value (weight and moisture corrected).

EXAMPLE

[0043] Line 1: ((75 g/70.6 * 820.40) * E ^(((−0.07499) * (13.50%-12.86%)) Line 2: 871.529 * E ^(−0.0479936) Line 3: 830.68 cc/100 g

[0044] Actual tests with a pilot plant apparatus showed that tobacco reordered with air at 110° F. and 58% relative humidity had a CFV of 687.1 and a moisture content of 10.5%. With air at 63% relative humidity and 110° F., the CFV was 613.4 and moisture content of 12.2%. Additional experimental results are set forth below in Table I: TABLE I 68% RH 73% RH 78% RH CFV ° F. Loss Mois CFV ° F. Loss Mois CFV ° F. Loss Mois  70  70  70  75  75  75  80  80 757.9  80 0  13.6 763.0  82 33.8 12.6 742.5  84 43.2 12.2  85  85  85 729.1  90 10.5 658.6  90 12.9 709.6  90 76.1 12.8 754.9  91 41.9 12.9  95  95 640.3  95 83.1 14.8 666.9 100 13.6 695.5 100 84.0 13.5 645.6 100 77.8 15.2 110 110 110 83% RH 88% RH 93% RH CFV ° F. Loss Mois CFV ° F. Loss Mois CFV ° F. Loss Mois 766.3  68 110.4 12.1 68 724.5  69 125.1 12.9 699.4 69 116.5 13.6  70  70  70  75  75  75 739.6  77 140.9 12.5  80  80 592.3  80 229.6 15.9  85  85  85  90  90  90  95  95  95 100 100 100 110 110 110

[0045] The data indicates the preferred temperature for the reordering process is between about 80° F. and 91° F., with tobacco showing signs of collapsing and resultant loss of filling value at temperatures higher than this range. Also, the relative humidity should be within the range of from about 73% to about 88% more preferably about 78%. However, a lower relative humidity, e.g., as low as about 58%, can be used, but with a corresponding increase in residence time being required, because the pickup of moisture into the tobacco is slower at lower relative humidity.

[0046] The samples tested were found to have average moisture content of 14.06% and a corrected fill value (CFV) of 758.2 cc/100 g. In comparison, expanded tobacco reordered in a rotating cylinder with spray nozzles to a moisture content of 14% exhibited a CFV of 670 cc/100 g. Thus, a significant increase of 13.6% in fill value was achieved. In addition, no significant changes in leaf content or smoking perception for conventionally-made cigarettes were noted. This is also true for cigarettes made with a low ignition propensity paper described in U.S. patent application Ser. No. 09/795,054 filed Feb. 26, 2001, the entire disclosure of which is incorporated herein by reference. These cigarettes exhibited the same reduced ignition propensity noted in that patent application.

[0047] Thus, the present invention provides a process and related apparatus that is effective in rapidly reordering tobacco with a reduction in the loss of filling power normally associated with expanded tobacco reordering processes. Among the advantages of the invention is the ability to have faster throughput, thereby reducing inventory costs and providing better control over the inventory, so that it can better suit just in time manufacturing schedules.

[0048] The apparatus is shown in FIG. 1 with the entrance end 18 of the conveyor 16 situated to receive the expanded tobacco as it drops by gravity from the rotary lock 14, and this is preferred for its simplicity. Conveyor 16 may comprise a vibratory conveyor or a moving belt conveyor. However, other configurations that keep the tobacco above about 80° F., and more preferably between about 180° F. and about 212° F., during transport from the lock to the source of humidifying air without causing its collapse may also be used. To this end, the expanded tobacco may be discharged from the sublimator into an enclosed heated conveyor (not shown) for delivery to the reordering zone. The enclosed conveyor is externally heated to maintain the elevated temperature of the tobacco between about 180° F. and about 212° F. until it is reaches the reordering zone. As with conveyor 16, the enclosed heated conveyor may be belted or vibratory.

[0049] The applicants have also found that the present process and apparatus also prevents the propagation of fire in the expanded tobacco bed after it is discharged from the sublimator. Specifically, the high velocity humidified air stream blown through the conveyor carrying the tobacco bed forms a fluidized bed of tobacco. Any hot embers discharged from the sublimator with the expanded tobacco are rapidly mixed in the fluidized bed of tobacco. Due to the high activity of the fluidized bed, fire propagation is eliminated because the embers have little, if any, contact with the tobacco. The embers quickly extinguish as they are consumed by their own fire.

[0050] This disclosure refers to humidified air, but it will be appreciated that other humidified gases such as humidified CO₂ or nitrogen may also work well in the practice of the invention, and should be considered as falling within the definition of “humidifying air” as used herein.

[0051] Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims. 

What is claimed is:
 1. A process for increasing the moisture content of expanded tobacco comprising contacting expanded tobacco having an initial moisture content of less than about 8% and an initial temperature of at least about 180° F. with an air stream having a relative humidity of from about 58% to about 88% and a temperature of from about 68° F. to about 91° F.
 2. The process of claim 1, wherein the expanded tobacco is disposed on a vibrating conveyor having an air permeable floor, the air stream flowing upwardly through the floor before contacting the expanded tobacco.
 3. The process of claim 2, wherein the expanded tobacco forms a tobacco bed on the floor of the conveyer, the tobacco bed having a depth of from about 0.10 inches to about 20 inches.
 4. The process of claim 2, wherein the air stream flows at a velocity of from about 10 CFM to about 120 CFM per square foot of the conveyor floor.
 5. The process of claim 1, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in less than 20 minutes after first being contacted by the air stream.
 6. The process of claim 1, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in from about 6 minutes to about 20 minutes after first being contacted by the air stream.
 7. The process of claim 1, wherein the expanded tobacco is cut tobacco filler.
 8. The process of claim 1, wherein the relative humidity of the air stream is from about 68% to about 78%.
 9. The process of claim 1, wherein the relative humidity of the air stream is about 78%.
 10. The process of claim 9, wherein the temperature of the air stream is about 90° F.
 11. A process for increasing the moisture content of expanded tobacco comprising contacting the expanded tobacco with an air stream having a temperature of from about 68° F. to about 91° F. and a relative humidity of from about 58% to about 88% as the temperature of the expanded tobacco decreases from an elevated temperature of at least about 180° F. to ambient temperature.
 12. The process of claim 11, wherein the expanded tobacco is disposed on a vibrating conveyor having an air permeable floor, the air stream flowing upwardly through the floor before contacting the expanded tobacco.
 13. The process of claim 12, wherein the expanded tobacco forms a tobacco bed on the floor of the conveyer, the tobacco bed having a depth of from about 0.10 inches to about 20 inches.
 14. The process of claim 12, wherein the air stream flows at a velocity of from about 10 CFM to about 120 CFM per square foot of the conveyor floor.
 15. The process of claim 11, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in less than 20 minutes after first being contacted by the air stream.
 16. The process of claim 11, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in from about 6 minutes to about 20 minutes after first being contacted by the air stream.
 17. The process of claim 11, wherein the expanded tobacco is cut tobacco filler.
 18. The process of claim 11, wherein the relative humidity of the air stream is from about 68% to about 78%.
 19. The process of claim 11, wherein the relative humidity of the air stream is about 78%.
 20. The process of claim 19, wherein the temperature of the air stream is about 90° F.
 21. A process for increasing the moisture content of expanded tobacco having an elevated temperature of at least about 180° F. when discharged from an expansion chamber, comprising contacting the expanded tobacco with an air stream having a temperature of from about 68° F. to about 91° F. and a relative humidity of from about 58% to about 88% before the temperature of the expanded tobacco decreases to ambient temperature.
 22. The process of claim 21, wherein the expanded tobacco is discharged from the expansion chamber onto a vibrating conveyor having an air permeable floor, the air stream flowing upwardly through the floor before contacting the expanded tobacco.
 23. The process of claim 22, wherein the expanded tobacco forms a tobacco bed on the floor of the conveyer, the tobacco bed having a thickness of from about 0.10 inches to about 20 inches.
 24. The process of claim 22, wherein the air stream flows at a velocity of from about 10 CFM to about 120 CFM per square foot of the floor.
 25. The process of claim 21, wherein the expanded tobacco is discharged from the expansion chamber into a heated chamber before being contacted with the humidified air stream.
 26. The process of claim 25, wherein the heated chamber comprises an enclosed heated conveyor.
 27. The process of claim 21, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in less than 20 minutes after first being contacted by the air stream.
 28. The process of claim 28, wherein the moisture content of the expanded tobacco is increased from less than about 8% to at least about 12% in from about 6 minutes to about 20 minutes after first being contacted by the air stream.
 29. The process of claim 21, wherein the expanded tobacco is cut tobacco filler.
 30. The process of claim 21, wherein the relative humidity of the air stream is from about 68% to about 78%.
 31. The process of claim 21, wherein the relative humidity of the air stream is about 78%.
 32. The process of claim 31, wherein the wherein the temperature of the air stream is about 90° F.
 33. A process for increasing the moisture content of expanded tobacco, comprising: (a) disposing expanded tobacco having an initial moisture content of less than about 8% and an initial temperature of at least about 180° F. on a conveyor having an air permeable floor, the tobacco forming a tobacco bed having a depth of about 9 inches; and (b) contacting the expanded tobacco for about 11 minutes with an air stream having a relative humidity of about 78%, a temperature of about 91° F. and a velocity of about 110 CFM per sq. ft. of the floor.
 34. An apparatus for increasing the moisture content of expanded tobacco, comprising: (a) an expansion zone for increasing the fill value of cut tobacco filler, the expansion zone having an outlet for discharging expanded tobacco having a moisture content of less than about 8% and an elevated temperature of at least about 180° F.; and (b) a reordering zone downstream of the expansion zone for receiving the expanded tobacco discharged from the expansion zone outlet, the reordering zone having a blower for blowing an air stream having a relative humidity of from about 58% to about 88% and a temperature of from about 68° F. to about 91° F. through expanded tobacco having an initial moisture content of less than about 8% and an initial temperature of at least about 180° F.
 35. The apparatus of claim 34, wherein the reordering zone comprises a conveyor having an air permeable floor, the air stream flowing upwardly through the floor before flowing through the expanded tobacco.
 36. The apparatus of claim 35, wherein the conveyor is a vibrating conveyor.
 37. The apparatus of claim 35, wherein the conveyor is a moving belt conveyor.
 38. The apparatus of claim 35, wherein the air stream has a relative humidity of about 78%, a temperature of about 90° F. and a velocity of about 110 CFM per sq. ft. of the conveyor floor.
 39. The apparatus of claim 34 further comprising a heated chamber for receiving the expanded tobacco discharged from the expansion zone and delivering the expanded tobacco to the reordering zone.
 40. The apparatus of claim 39, wherein the heated chamber comprises an enclosed heated conveyor.
 41. A process for preventing the propagation of fire in a bed of expanded tobacco discharged from an expansion zone, comprising: (a) forming a bed of expanded tobacco having a depth of between about 0.10 inch and about 20 inches on a conveyor having an air permeable floor; and (b) contacting the expanded tobacco with an air stream having a velocity of from about 10 CFM to about 120 CFM per square foot of the conveyor floor to create a fluidized bed of expanded tobacco.
 42. The process according to claim 41, wherein the bed of expanded tobacco has a depth of about 9 inches and the air stream has a velocity of about 110 CFM per sq. ft. of the conveyor floor. 